VC2013 move operator doesn't recursively perform move

The following code doesn't compile in VS2013.

#include <memory>
#include <vector>

struct Struct {
  std::unique_ptr<int> data;
};

int main() {
  std::vector<Struct> vec;
  vec.emplace_back();
  vec.emplace_back();
  vec.front() = std::move(vec.back());
  return 0;
}

I get the following error:

error C2280: attempting to reference a deleted function

It seems like VS compiler is trying to call the assignment operator while the code explicitly requests a move. Is this a bug? Are there any workarounds for this problem?